Tap.



' E V By his W0. A. SMITH. TAP.

APPLIOATION FILED AUG. 16, 1906. RENEWED MAR. 11, 1908.

899,916. v Patented Sept. 29,1908.

Witnesses: In ventor;

- osoia A. SMITH. or cLEvELAu-D, onio. assieroa To EDWIN 0. near, or CLEVELAND, 01110.

To all whom it may concern;

a citizen of the United States, residingiin 1 mm strAI S TAP.

- Application filed August is, 1006, semi No. 880,894. Renewed. Inch 11, 1908. ca-n1 No. 420,450.

Be itknown that I, Oscar Atroosfr SMITH,

Cleveland, in the county of- Cuyahoga and State of Ohio,' have invented certain new and useful Improvements in Taps, of which the following is a s ecification. v

This invention re ates to tools for cutting threads in nuts or in the bores of any other member; and has for its object torovide a; tap that will operate to cut identically the same thread u on either end being inserted in the bore an the tap iven a spiral movement in the proper direction. In other words, the tap will operate'in eitherendwise direction to cutthe same thread in the bore of a member.

In' the accompan ing drawing, re resenting embodiments o my invention, igure 1,

is a plan view of one form of tap. Fig. 2 is an end view of the same. Fig. 3 is an end view of Fig. 1 showing the end portion only of the tap. Fig. 4 shows a slightly modified form of ta' Fig. 5 is an end view of the tap shown in Fig. 4. Fig. 6 is an end view of the tap shown in Fig. 4 showing the end portion only. Fi 7 shows enlarged a section taken on the ine 7-7 indicated in Fig. 4. Fig. 8 is a similar view on the line 8-8 indicated in Fig. 4. Fig. 9 is a similar view on the line 99 indicatedin Fig. 4. Fig. 10 is a similar view taken on the line 10-10indicated in Fig. 4. Fig. 11 shows the tap as moving endwise in one direction into a nut-1 blank to cut a thread therein; and Fig. '12 shows the same tap as operating in the opposite endwise direction on a nut-blank t thread the same. 1

The tap is provided with a circular series of longitudinal extending cutter members, in the present instance four such cutters being shown, but obviously a greater, or less number could beused. In Fig. 1 is shown a shank A provided. with four cutter members, a, b, c and d, which cutter members are separated by flutes e, f, g, and h. Here tofore, taps have been constructed with the cutters having full threads at the portion the threa In the present invention, the cutters have the teeth the full height or .outer diameter at the intermediate portion or middle part of each cutter member, while the teeth are tapred from this middle portion towards each end of the cutter member.- That is, the di-- ameter of the teeth of the cutter portion decreases from the middle portion of the cuttertowards each end thereof. By reason of this construction, the tap can have either end r mit-ea Beet. 29, 1908.

of the cutter portion inserted in a nut blank or the'bore of any member, and be passed entirely through the member; while another nut or member can have the same ta inserted' from its 0 posite end, the tap ein now rotated in t e opposite direction, an the thread formed in the second nut will be identical with that formed in the first nut.

In the forms of tap at present in use, the threads at the smaller reduced end, that first engages the nut lank, are given an inclina-.

tion or rake that extends backward or in the reverse direction of the rotation of the ,tap to produce the thread. This will produce a cutting member {that will have clearance, whereby its transverse cutting edge, which is a portion of the flute, will, operate to remove the metal more easily to start the thread. In the present invention, the reduced portion of the cutters at both ends of the cutting partof the tap are given a rake, but the rake at the two ends will extend in opposite directions. This for the reason that when either end is inserted in the nutblank, as for instance the end z in the nut N in Fig. 11, the reduced cutter teeth will have a negative rake in the direction of rotation. But when the end is of the tap is first passed into the nut blank and the tap is rotated in the opposite direction, the teeth on the reduced portion of the tap adjacent the end is will have a negative rake, and this will be adjacent the end is. At the middle portion of the tap as indicated in Fig. 10, the teeth are preferably of uniform diameter at, or equidistant from the axis, no rake being given to them.

. This form of tap is of particular importance when used in an automatic machine,

wherein nut blanks are successively fed to a' certain lace, and there tapped by the operation oi the machine. With such a machine, it is desirable to 'form a double end tap having the cutter portion at the interme iate part of the shank, as shown in the drawings. With such a machine, the tap can be mtroduced into the nut-blank from one end, and spirally advanced to cut the thread; and then the endwise movement of the tap is continued to pass entirely through the blank. Thereupon the blank is ejected, and another blank secured in the same position. Then the tap can he moved back through the same path as before in the opposite spiral direction, being iven a reverse 'rotative movement. This Wlll have the effect of producing identically the same thread in the second nut blank as was produced in the first; and so on, a large number of blanks can be successively tapped, one being threaded at each endwise movement of the tap. An application for patent on such a nut ta ping machine was filed by me on the 24th ay of August, 1906, Serial Number 331,825.

The shank of the tap may have the flutes e, f, g and h continued to each end, as indicated in Figs. 4 and those following. Or, if desired, the shank of the tap may be cylindrical, but have reduced portions m at each end, as shown in Figs. 1 and 3, for engaging in the sockets of two opposed operating members.

Having thus described my invention, I claim:

1. A tap comprising an integral double ended shank having the rigid cutter portion formed at the intermediate part of the shank, the diameter of the s iral threads decreasing from the middle 0 the cutter portion toward each end of such portion, the

separate cutters or teeth .at one end of each of the longitudinal cutter members having a circumferential rake, the se arate cutters or teeth at the oppos te end 0 the cutter portion being given a circumferential rake extending in a rotative direction the opposite to that at the other end.

2. A tap comprising an integral double ended shank having the rigid se arate cutters or teeth at one end of each 0 the longitudinal cutter members of the tap given a circumferential rake, the separate cutters or teeth at the opposite end of the cutter por tion being given a circumferential rake extending in a rotative direction the opposite to that at the other end, the cutters or teeth at the middle part of the longitudinal cutting members, being of substantially uniform height or outside diameter throughout their peripheral length.

3. A tap comprising a shank having aplurality of sets of cutters, each set tapered from the middle part thereof toward the end of the cutters, the teeth at one end of each set having'a different rake or inclination from the teeth at the opposite end of the same set, whereby said tap is operative to cut the same thread starting from either end of said tap.

4. A tap comprising a shank having a set of cutters, the teeth at one end of each set having a different rake or inclination from the teeth at the opposite end thereof and said teeth constructed to enter a blank, whereby said tap is operative to cut the same starting from either end of said tap.

OSCAR A. SMITH.

Witnesses:

' O. S. WENITZ,

A. W. HENN. 

